To meet the demand for wireless data traffic, which has increased since deployment of 4th-generation (4G) communication systems, efforts have been made to develop an improved 5th-generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘beyond 4G network’ or a ‘post long-term evolution (LTE) system’.
It is considered that the 5G communication system will be implemented in millimeter wave (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To reduce propagation loss of radio waves and increase a transmission distance, a beam forming technique, a massive multiple-input multiple-output (MIMO) technique, a full dimensional MIMO (FD-MIMO) technique, an array antenna technique, an analog beam forming technique, and a large scale antenna technique are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, a device-to-device (D2D) communication, a wireless backhaul, a moving network, a cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation, and the like.
In the 5G system, a hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and a sliding window superposition coding (SWSC) as an advanced coding modulation (ACM) scheme, and a filter bank multi carrier (FBMC) scheme, a non-orthogonal multiple Access (NOMA) scheme, and a sparse code multiple access (SCMA) scheme as an advanced access technology have been developed.
Recently, study for increasing a frequency efficiency and a data rate has actively progressed as data traffic has been explosively increased. A MIMO scheme is a scheme in which a plurality of data streams can be transmitted at once using a plurality of transmission antennas and a plurality of reception antennas, and has an advantage of increasing a data rate proportionally to the number of antennas.
Meanwhile, a linear scheme such as a zero-forcing (ZF) method, a minimum mean squared error (MMSE) method, and/or the like and a non-linear scheme such as a maximum likelihood (ML) estimating method, a sphere decoding method, and/or the like have been proposed as a general MIMO transmitting/receiving method.
The non-linear scheme has relatively good performance and a high complexity. More particularly, if the number of antennas is increased, complexity of the non-linear scheme is exponentially increased.
Further, complexity of the linear scheme is low than the complexity of the non-linear scheme, but performance of the linear scheme is bad than performance of the non-linear scheme.
For overcoming a weakness of existing schemes such as the linear scheme and the non-linear scheme, an integer forcing (IF) scheme of which complexity is similar to complexity according to an existing linear scheme and performance is similar to performance of a non-linear scheme, e.g., an ML estimating method which provides optimal performance has been proposed.
Unlike existing schemes, the IF scheme is a scheme of decoding a sum of codewords based on a fact that a modular sum of linear codes becomes another code. If the IF scheme is used, a noise amplification issue which occurs when existing linear schemes are used can be prevented. Here, the noise amplification issue can be, for example, a noise amplification issue which occurs when a multiple stream is de-multiplexed.
The IF scheme has been proposed assuming a case that a channel is not changed according to a time and symbols of codewords transmitted through each antenna are transmitted on the same channel, so it may be difficult to apply the IF scheme to an actual channel environment.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.